When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Over simplifying I’d say that more lockup helps at higher speeds but hurts at lower speeds. To understand why:
Consider the extreme case where you’ve locked the rear wheels together with a spool (100% lockup). This is bad particularly around tight radius bends: the rear always wants to track straight and you need to drag/ slip the tires relative to one another to overcome this. This results in extreme understeer at lower speeds, with the front always fighting to overcome the rear. Bad at an autocross, which is why the advice is often to ditch a clutch type LSD entirely and go to a torque biasing diff, which does not induce understeer.
At high speeds things change. As corner radius increases the difference between the inside and outside wheel-speed decreases, so the dragging/ understeer is dramatically reduced. Second and more importantly the car’s overall handling balance shifts towards oversteer, so you actually want some understeer in the mix to stabilize it. Hence the advice that track cars get clutch type LSD with plenty of lockup to add stability.
Hence the simplification that the R’s LSD is biased towards tighter bends/ lower speeds and the GT3’s biased towards larger bends and higher speeds.
Great looking cars gang, hope you guys are enjoying driving them. Miami Blue looks really good and would have been a great non-PTS back-up color for me. Any of you guys got through break-in and rev'ed the cars near 9k RPM yet?
Finally got a chance to drive the new arrival (45 degrees and clear in SW Ohio). Certainly lightyears ahead of its stablemate in refinement but may be missing a bit of the steering feel/feedback which I love in the 6GT3. Only put about 75 miles on it today and am wondering how anyone can possibly keep the engine below 4000rpm for the initial 2000 mi break in period...
Location: The way to hell is paved by good intentions “Wenn ich Purist höre...entsichere ich meinen Browning” "Myths are fuel for marketing (and nowadays for flippers too,,,)" time to time is not sufficient to be a saint, you must be also an Hero
Over simplifying I’d say that more lockup helps at higher speeds but hurts at lower speeds. To understand why:
Consider the extreme case where you’ve locked the rear wheels together with a spool (100% lockup). This is bad particularly around tight radius bends: the rear always wants to track straight and you need to drag/ slip the tires relative to one another to overcome this. This results in extreme understeer at lower speeds, with the front always fighting to overcome the rear. Bad at an autocross, which is why the advice is often to ditch a clutch type LSD entirely and go to a torque biasing diff, which does not induce understeer.
At high speeds things change. As corner radius increases the difference between the inside and outside wheel-speed decreases, so the dragging/ understeer is dramatically reduced. Second and more importantly the car’s overall handling balance shifts towards oversteer, so you actually want some understeer in the mix to stabilize it. Hence the advice that track cars get clutch type LSD with plenty of lockup to add stability.
Hence the simplification that the R’s LSD is biased towards tighter bends/ lower speeds and the GT3’s biased towards larger bends and higher speeds.
yes but i guess the .2 GT3 drivers can use a little less the throttle in tight corner to get the same R transferred torque or less whilst R can't do the opposite
yes but i guess the .2 GT3 drivers can use a little the throttle in tight corner to get the same R transferred torque or less whilst R can't do the opposite
It’s true the push issues can be driven around- you can even make a solid spool work at the autocross if you’re aggressive enough, at least once in a while. Far less than ideal though.
The torsion diff is particularly interesting in that rather than lock the wheels together it directs more thrust to the wheel with more traction (outside). Thus unlike a traditional LSD which increases understeer it actually uses the engine’s power on the outside wheel to help rotate the car, great for tight corners. Unfortunately it doesn’t do a thing under braking, so it’s no help on high speed corner entry. Little wonder that the industry is moving towards electronic control to get the best of all worlds.
12-16-2017, 12:31 PM
